Fig. 5.

Hypothesis on the OPG mechanisms of action in Ewing's sarcoma by binding TRAIL. (A) ES cells were cultured for 48 h in the presence of OPG. OPG has no direct effect on ES cell proliferation in vitro. (B) TRAIL is expressed in ES tumor models. Assays were realized on protein lysats obtained from fragments of tumors induced by intramuscular injection of human Ewing's sarcoma A-673 cells in nude mice, and normalized to respective protein levels (N=number of tumor samples analyzed). (C) The production of TRAIL was analyzed at the mRNA level by real time PCR in 10 ES cell lines and compared to human MSCs. (D) Two Ewing's sarcoma biopsies were analyzed for TRAIL immuno-staining (see Section 2) (original magnification 20×).